Eu_1.8La_0.2BaZnO₅: a Rietveld refinement using X-ray powder diffraction

The families of oxides with stoichiometry RE₂BaMO₅ (where RE is a trivalent rare earth, and M is Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Pd²⁺ or Pt²⁺) are known as the green phases in studies of Y-Ba-Cu-O superconductor ceramics. These oxides are not superconductors but nevertheless present interesting structural types. In this work, the synthesis and structural characterization using the Rietveld method applied to X-ray powder diffraction data for Eu_1.8La_0.2BaZnO₅ (europium lanthanum barium zinc oxide) are presented. The compound is isostructural with Y₂BaZnO₅. The two sites for Y³⁺ are occupied by Eu³⁺, while La³⁺ ions partially occupy one of these sites.

Key indicators

• Powder X-ray study
• T = 300 K
• Mean [sigma](n-O) = 0.014 Å
• Disorder in main residue
• R factor = 0.000
• wR factor = 0.000
• Data-to-parameter ratio = 23.3

checkCIF/PLATON results

No syntax errors found



Alert level A
GEOM005_ALERT_1_A  _geom_angle_atom_site_label_1 is missing
            Label identifying the atom site 1.

Alert level C
REFI015_ALERT_1_A  _refine_ls_shift/su_max is missing
            Maximum shift/s.u. ratio after final refinement cycle.
            The following tests will not be performed
            SHFSU_01
REFI023_ALERT_1_C  _refine_diff_density_max is missing
            Maximum value of final difference map (e A-3).
            The following tests will not be performed
            DIFMN_01,DIFMX_01,DIFMX_02
REFI024_ALERT_1_C  _refine_diff_density_min is missing
            Minimum value of final difference map (e A-3).
            The following tests will not be performed
            DIFMN_01,DIFMN_02,DIFMN_03
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.25 Ratio
PLAT077_ALERT_4_C Unitcell contains non-integer number of atoms ..          ?
PLAT128_ALERT_4_C Non-standard setting of Space group Pnma    ....    Pbnm
PLAT301_ALERT_3_C Main Residue  Disorder .........................      10.00 Perc.

   2 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   7 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   6 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: DIFFRAC/AT (Siemens, 1993); cell refinement: Please provide details; program(s) used to solve structure: Please provide details; program(s) used to refine structure: FULLPROF (Rodríguez-Carvajal, 1990); molecular graphics: ATOMS (Dowty, 2000); software used to prepare material for publication: ATOMS.

europium lanthanum barium zinc oxide

Crystal data

Eu1.8La0.2BaZnO5	F(000) = 1003.2
Mr = 584.03	Dx = 7.4 (1) Mg m^−3
Orthorhombic, Pbnm	Cu Kα radiation, λ = 1.54175 Å
Hall symbol: -P 2c 2ab	T = 300 K
a = 7.1952 (1) Å	Particle morphology: homogeneous micrometric particles
b = 12.5720 (2) Å	pale yellow
c = 5.8035 (1) Å	flat_sheet, 20 × 20 mm
V = 524.97 (1) Å^3	Specimen preparation: Prepared at 1473 K
Z = 4

Data collection

Siemens D5000 diffractometer	Data collection mode: reflection
Radiation source: sealed X-ray tube, Cu Kα	Scan method: step
Graphite monochromator	2θmin = 10.025°, 2θmax = 110.025°, 2θstep = 0.020°
Specimen mounting: packed powder sample container

Refinement

Refinement on Inet	Profile function: pseudo-Voigt modified by Thompson et al. (1987)
Rwp = Please supply	34 parameters
RBragg = 0.071	0 restraints
5001 data points	Background function: linear interpolation between a set background points with refinable heights

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Eu1	0.1163 (3)	0.29211 (14)	0.25000	0.0035 (5)
Eu2	0.3975 (3)	0.07426 (15)	0.25000	0.0014 (5)	0.8
La	0.3975 (3)	0.07426 (15)	0.25000	0.0014 (5)	0.2
Ba	0.9268 (3)	0.90100 (14)	0.25000	0.0019 (5)
Zn	0.6846 (6)	0.6500 (3)	0.25000	0.015 (1)
O1	0.156 (2)	0.4235 (12)	−0.016 (2)	0.014 (2)
O2	0.362 (2)	0.2315 (10)	0.489 (2)	0.014 (2)
O3	0.088 (3)	0.1018 (14)	0.25000	0.014 (2)

Bond lengths (Å)

Eu1—O1	2.28 (2)	Ba—O1^ix	3.38 (1)
Eu1—O1^i	2.28 (2)	Ba—O1^x	3.38 (1)
Eu1—O2	2.37 (1)	Ba—O1^xi	3.24 (1)
Eu1—O2^ii	2.39 (1)	Ba—O2^ix	2.96 (1)
Eu1—O2^iii	2.39 (1)	Ba—O2^xii	3.07 (1)
Eu1—O2^i	2.37 (1)	Ba—O2^xiii	3.07 (1)
Eu1—O3	2.40 (2)	Ba—O2^x	2.96 (1)
La—O1^iv	2.31 (1)	Ba—O3^xiv	2.78 (2)
La—O1^v	2.47 (2)	Ba—O3^xii	2.904 (1)
La—O1^vi	2.47 (2)	Ba—O3^xv	2.904 (1)
La—O1^vii	2.31 (1)	Zn—O1^xv	2.00 (1)
La—O2	2.43 (1)	Zn—O1^xvi	2.00 (1)
La—O2^i	2.43 (1)	Zn—O2^xii	2.15 (1)
La—O3	2.25 (2)	Zn—O2^xiii	2.15 (1)
Ba—O1^viii	3.24 (1)	Zn—O3^xvii	2.05 (2)

Symmetry codes: (i) x, y, −z+1/2; (ii) x−1/2, −y+1/2, −z+1; (iii) x−1/2, −y+1/2, z−1/2; (iv) x+1/2, −y+1/2, −z; (v) −x+1/2, y−1/2, −z+1/2; (vi) −x+1/2, y−1/2, z; (vii) x+1/2, −y+1/2, z+1/2; (viii) x+1/2, −y+3/2, −z; (ix) −x+3/2, y+1/2, −z+1/2; (x) −x+3/2, y+1/2, z; (xi) x+1/2, −y+3/2, z+1/2; (xii) −x+1, −y+1, z−1/2; (xiii) −x+1, −y+1, −z+1; (xiv) x+1, y+1, z; (xv) −x+1, −y+1, z+1/2; (xvi) −x+1, −y+1, −z; (xvii) −x+1/2, y+1/2, −z+1/2.